The reason "Cheap Sells" is because "quality" and DURABILITY go much deeper than just what you can see and touch. It is difficult (impossible ?) for the average person to see the difference between an average (or even sub-average) quality RV and an above average quality one.
I applaud Jayco's Magnum Roof System (curved roof, no chance for water to pool), but they still need a better flashing system to get the rain off the roof and prevent the windows from leaking. Water intrusion is DEATH to RVs with wood floors.
Molded fiberglass ("eggshells") appear to be the way to go, but most are small and very expensive (Is it the materials or is it the low volume ?)